Tickets can be used across the transport providers with a basic pass which is valid for 24, 48 and 72 hours and has unlimited connections. The tickets must be validated before boarding the Metro and on board the trams to avoid a fine. Striptickets work according to the number of zones you travel through. These are available in amounts of 8, 15 and 45. All tickets can be purchased from GVB outlets, newsagents, supermarkets and post offices.